The increasing usage of the world's petroleum resources for combustion is rapidly depleting known reserves. A corresponding problem exists due to increasing pollutants being generated by internal combustion engines. These pollutants threaten the health of residents in metropolitan areas throughout the world. Legislation has been enacted to force automobile and truck manufacturers to control emissions and to increase engine efficiency. More legislation in this area is anticipated.
The general conditions of combustion, especially regarding internal combustion engines, are well known. The Spark Ignition engine (SI) requires a near stoichiometric mixture of fuel and air to be supplied to a combustion chamber. The mixture is compressed by a piston and ignited by a spark plug providing energy of combustion to drive the piston downward creating the power stroke. Ideally, with a perfect fuel and air mixture, uniform distribution throughout the cylinder, and perfect flame front ignition, the hydrocarbon fuel would be completely burned with a resulting exhaust mixture of CO2, H2O, and nitrogen. This ideal environment, however, cannot be achieved in the real world. Real world conditions include incomplete combustion and less than ideal efficiencies of thermodynamic cycles. The actual conditions that exist in internal combustion engines result in polluting exhaust products of unburned hydrocarbons, oxides of nitrogen (NOx), carbon monoxide and particulate matter.
The design of the SI engine to increase fuel efficiency requires a higher level of refining of the petroleum stock along with the production and addition of a number of additives to prevent pre-ignition and the corresponding engine damaging knock. The high compression of these engines also results in higher combustion temperatures that generate oxides of nitrogen along with other products that pollute the immediate surroundings. The two-stroke SI engine is an inherent polluter. Unburned fuel and lubricating oil exit with the products of combustion in the exhaust.
The other major engine design is that of the Diesel Compression Ignition engine (CI). In this engine, the charge of fuel and air mixture is ignited spontaneously due to the heat generated when a high level of cylinder compression is achieved. The CI engine has several advantages over the SI engine. It requires a less refined and cheaper fuel. The high compression ratio and leaner fuel to air mixture results in a more efficient combustion of the fuel from an energy recovery point of view. The CI engine, however, has some serious drawbacks. The exhaust of its unburned fuel contains particulate and other gaseous pollutants, such as sulfur compounds, due to its less refined fuel stock.
It is again being proposed to put in place government mandated increases in fuel efficiency to obtain improved manufacturers' fleet mileage in the United States. The original approach by manufacturers was to achieve fuel efficiency by weight reduction and reduction of vehicle size. The automobile owning public would only accept size reduction to a point where the passenger compartment was found to be too small. The smaller automobiles were also found to be less crash resistant resulting in more accident fatalities, especially when involved with a significantly larger and heavier vehicle. Recently, the move by the driving public in the United States to sport utility vehicles with significantly larger size/weight and a corresponding lowered gas mileage, has been a contradiction to the problem.
Over the years, there have been numerous attempts to increase fuel efficiency in internal combustion engines. Along with mechanical engine design changes, there have been attempts to further increase engine efficiency and reduce pollutant products by attacking the problem in the cylinder combustion by modifying the condition of the fuel supplied to the cylinder. One attempt has been to increase fuel atomization by utilizing higher fuel pressure and smaller orifice injection nozzles to achieve improved combustion due to the formation of smaller sized fuel droplets thus aiding evaporation. Another combustion improvement has been to control the fuel injection sequence in such applications as stratified charge injection. Success in reducing pollutants at their source, the combustion zone, has been limited and the emphasis by manufacturers, government and academia researching this problem, has concentrated on the exhaust system.
There have also been significant attempts to improve combustion efficiency of a fuel by treating various parts of the combustion process, the first is precombustion treatment of the fuel or air supply or both. The second is treatment within the combustion zone, and the third is exhaust pollutant treatment, such as improvements to the catalytic converter.
Precombustion Treatment
One of the first proposals for increasing engine efficiency was to preheat the fuel or fuel mixture before it entered the cylinder. U.S. Pat. No. 4,524,746 describes the use of a closed vaporizing chamber and heats and vaporizes fuel with an ultrasonic transducer. U.S. Pat. No. 4,672,938 describes the use of fuel heating and a second fuel activation device to achieve hypergolic combustion. U.S. Pat. No. 6,202,633 de scribes the use of a reaction chamber with heat and an electric potential to treat the fuel. One obvious disadvantage of preheating the fuel and/or fuel to air mixture, is the fact that less mass of combustibles will be transferred to the combustion chamber now that they are at higher temperatures. This will result in a reduction in horsepower for the same displacement volume engine. Note that a common approach in Diesel engines of today, is the use of turbochargers with an air aftercooler to cool the compressed air which supplies more mass of air to facilitate combustion and increase engine horsepower.
Another early method attempting to increase engine efficiency dealt with treating the fuel with a magnetic field as it is supplied to the fuel/air stream to increase its combustibility. Reasoning behind this approach cited the successful molecular rearrangement by the magnetic treatment of water circulated within piping in the water treatment and chemical industry. These water magnetic treatment devices are used to prevent mineral scaling or remove mineral scale that builds up with time. These devices have been somewhat successful in replacing chemical treatment.
There are numerous devices relating to magnetic treatment of fuel lines claiming to obtain enhanced combustibility of the fuel supply and a reduction in pollutants. These devices are described in U.S. Pat. Nos. 4,572,145, 4,188,296 and 5,129,382, in which permanent magnets are attached to the fuel line prior to introduction of fuel into an air mixing duct. The mixture is then drawn into the combustion mixing zone of an internal combustion engine. These patents claim that molecular fuel agglomerates are reduced and free radical and ionized fuel components are produced in the fuel thereby enhancing combustion resulting in increased fuel mileage and engine horsepower.
Electric field treatment of fuels has also been proposed. The use of dielectric beads between electrodes to treat the flow through fuel is described in U.S. Pat. No. 4,373,494. U.S. Pat. No. 5,167,782 describes a voltage being placed on a special metal composition which is in contact with the fuel.
The permanent magnets can be replaced with electromagnets as claimed in U.S. Pat. No. 4,052,139. Still further treatment of the fuel feed is accomplished by the use of ultrasonic, UV, and IR radiation described in U.S. Pat. Nos. 4,401,089, 4,726,336 and 6,082,339, respectively.
Catalytic treatment of fuels or its combination with other devices has been described. U.S. Pat. No. 5,451,273 claims that a special cast alloy fuel filter will improve combustion efficiency by catalytic means. U.S. Pat. No. 4,192,273 claims metal plates plated with a palladium catalyst being placed within the intake manifold to create turbulence and mix the catalyzed gases enhances combustion. Turbulent flow of the fuel over several catalytic screens of different metals to catalytically condition the fuel is also described in U.S. Pat. No. 6,053,152.
A far infrared ray emitting device placed within the fuel line to aid combustion is described in U.S. Pat. No. 6,082,339.
Treatment of air or gaseous fuel mixtures by magnets for internal combustion engines, has also been described, with the object of reducing emissions in U.S. Pat. No. 6,178,953. U.S. Pat. Nos. 4,572,145 and 4,188,296 also describe the treatment of air or air/fuel mixtures with magnets.
The combustion air supply can be treated with electric fields. There are a number of precombustion ionization devices that generate high strength electric fields to ionize air in the air supply. U.S. Pat. Nos. 5,977,543 and 5,487,874 are notable.
Means other than magnets or electric fields to treat fuel or air or air/fuel mixtures to increase engine efficiency are described in a significant number of United States patents. They apply combustion enhancing treatment either to the combustion air stream or to the fuel/air stream to increase fuel efficiency. Enhancement mechanisms include IR and electromagnetic field energy as cited in U.S. Pat. No. 6,244,254. High voltage ion generators are used to treat air in U.S. Pat. No. 5,977,716. U.S. Pat. No. 6,264,899 claims the conversion to the hydroxyl radical and other radical species in the air stream, can be achieved by the use of primarily UV radiation and secondarily Corona discharge devices in the supply air stream.
Despite the numerous inventions addressing this problem, there still exists a need for improved enhancement of combustion.
Precombustion Treatment-Injector Nozzles
The pressure of the fuel supply to the fuel injectors has been increased over time in internal combustion engine development. The goal has been to produce smaller fuel droplets. Injection pressures for the Gasoline Direct Injection engine (GDI) are as much as ten times those of the present fuel/air intake systems.
Another method of heating fuel prior to the combustion chamber is located at the nozzle itself. U.S. Pat. No. 5,159,915 describes heating the complete injector by an electromagnetic coil that generates a fluctuating magnetic flux density. It also uses a magnetically sensitive material in the nozzle section to concentrate the heating magnetic field.
Another goal in fuel injection has been to charge the fuel droplets. U.S. Pat. No. 4,051,826 describes the fuel tube and injector nozzle being charged to a high electrical potential to charge the fuel droplets, conditioning the fuel droplets for efficient combustion. U.S. Pat. No. 4,347,825 describes the use of high voltage to electrify fuel particles to prevent them from attaching to the oppositely charged surrounding walls of a fuel passage. It uses an electrode near the injector nozzle.
U.S. Pat. No. 6,305,363 uses an air assisted fuel injector that injects directly into the combustion chamber of a Direct Injection Engine. The air supplied to the injector is ozone enriched to assist in the combustion process.
Despite the numerous inventions addressing this problem, there still exists a need for improved enhancement of combustion.
In-Cylinder Combustion Enhancement
This category can be divided into two subcategories. The first is treatment that supplies combustion enhancing chemical compounds to the combustion zone such as ozone. The second are devices that apply combustion enhancing energy to the combustion chamber itself.
An early combustion enhancing compound that was added to internal combustion engines was water. Water injection has been used in internal combustion engines since the first decade of the century. The original purpose was for engine cooling. It was later shown to give octane improvement and was used in aircraft engines. U.S. Pat. No. 4,018,192 describes injecting water directly into the combustion chamber through the spark plug opening to increase power and fuel economy. U.S. Pat. No. 5,255,514 also describes using water vapor to increase engine efficiency. U.S. Pat. No. 6,264,899 describes improving engine performance by adding the (—OH) radical obtained by treating a high water vapor/air stream with UV radiation or an electrical discharge device to improve combustion.
U.S. Pat. No. 4,308,844 describes using an ozone generator in the air supply to produce ozone and positively charged particles. U.S. Pat. No. 5,913,809 describes an ionization field across the air flow path producing ozone for both the intake and exhaust systems. A UV light source could be substituted to ionize the oxygen in the air stream.
A method of irradiating inlet air by alpha-decay to transform by fission, a part of nitrogen in the air into monatomic oxygen, and monatomic hydrogen to reduce toxic components in the exhaust stream, is contained in U.S. Pat. No. 5,941,219.
The concept of adding energy directly to the combustion chamber is described in U.S. Pat. No. 5,983,871 where a laser beam is introduced within the cylinder to decrease the slow initial stage of laminar combustion, therefore improving the combustion process. U.S. Pat. No. 4,176,637 has a high voltage electrode within the combustion chamber surrounding the fuel injector fuel stream to charge the fuel particles.
Despite the numerous inventions addressing this problem, there still exists a need for improved enhancement of combustion.
Exhaust Stream Treatment
Following the successful development of the catalytic converter for the SI engine, the activities surrounding further exhaust treatment were limited. There has been recent worldwide government action mandating further reduction in pollutants for the Diesel engine. A very significant effort by manufacturers, affected government agencies and academia has been and is currently underway in the United States to solve the remaining exhaust pollution problem.
The existing catalytic converter for the SI engine cannot be successfully used for the CI engine exhaust stream. The problem of excessive particulate is being addressed with a particulate trap technology. These traps must be regenerated and fuel addition to the trap is one method being developed. NOx traps are also under development.
The sulfur component in the exhaust fouls the existing catalyst types and alternate catalyst development is underway, faced with a complex problem. One solution is the refining of fuel to remove the sulfur compounds. Another possible solution under investigation is to add reducing compounds such as ammonia, or urea to undergo a chemical reaction with exhaust compounds in the exhaust stream.
Another area of research is the application of a non-thermal plasma device to oxidize pollutants. Combining this technology with a following catalyst section is actively being pursued.
Cold start pollution and catalyst light off are problem areas being addressed.
There has been a recent increase of inventions in this exhaust area of investigation. Some of these utilize very sophisticated sensor detection and computer control of engine operation within lean and rich mixtures.
U.S. Pat. No. 6,264,899 presents a method using UV radiation to produce hydroxyl ions in the exhaust stream to reduce pollutants. U.S. Pat. No. 5,913,809 claims the addition of ozone to the exhaust stream to reduce pollutants.
A significant number of U.S. patents have issued for catalyst systems. U.S. Pat. No. 6,294,141 uses a two catalyst system for a Diesel engine where the soot formed on the second catalyst is combusted by NO2 containing gas from the first catalyst.
Heretofore, efforts to enhance combustion in the combustion zone have not been earnestly pursued and emphasis has been placed on the cleanup of exhaust pollutants by several means.
It is clear that a myriad of means to add energy or alter the combustion process has been put forth but is fragmented and not based on a sound unified theory explaining results. Most of these fragmented solutions have not included practical, economic hardware devices for their implementation. It is the purpose of this invention to present a method and apparatus that will solve the problems of incomplete combustion and exhaust gas pollutant control.